Double-loop directional element



July 10, 1945.

S. L. GQLDSBOROUGH ETAL DOUBLE-LOOP DIRECTIONAL-ELEMENT Fild Sept. 22, 1945 WITNESSES:

INVENTORS L. fiolabwg'oa 22 220 ATTORNEY Patented July 10, 1945 2,380,165 DOUBLE-LOOP DIRECTIONAL ELEMENT Shirley L. Goldsborough, Basking Ridge, and Arthur C. Mehring, East Orange, N. 1., asslgnors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 22, 1943, Serial No. 503,366

12 Claims.

Our invention relates to the elimination of the double-frequency pulsating torque-component of the high-speed loop-type wattmetric or directional relay. This pulsating torque has heretotore caused considerable difliculty in the operation of directional elements, especially at phaseangles which are close to the angle of zero-torque, or balance-point, of the element.

It has been known, heretofore, that this doublefrequency torque can be eliminated by combining two directional elements, one of which has both its current and its voltage shifted 90 with respect to the current and voltage, respectively, of the other. Such a double-element device is shown in Fig. 4 of Patent No. 2,300,886, issued to the present applicant Goldsborough, and Bert V. Hoard, on November 3, 1942. It has three major disadvantages, first, in requiring two elements, second, in requiring a 90 external phase-shifter in the current-circuit, and, third, a 90 external phase-shifter in the voltage-circuit. A 90 phaseshifter is both difiicult and expensive to achieve, without reducing the effective energy-producing torque on the element to a small and ineflective quantity.

It is the principal object of our invention to produce a practical type of non-vibrating singlephase directional-element, requiring only one element, and no external phase-shifters, to obtain the two torques having their pulsating components displaced 90 in time (on a normal-frequency basis), so as to produce a non-vibrating or constant-torque directional response.

Generally speaking, it is an object of our invention to utilize two loops, responding to the product of two alternating fluxes, times a function of the phase-angle displacement between them, in'such manner that one loop is traversed, or excited, by one of the fluxes, and has its coilsides or a coil-side thereof reacting with the second flux, while the other loop is traversed or excited by the second flux and has its coil-side or sides reacting with the first flux.

with the foregoing and other objects in view, our invention consists in the circuits, apparatus, systems, parts, constructions, and methods, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

Figure 1 is a diagrammatic plan-view of circuits and apparatus showing our invention in an illustrative form of embodiment; and

' Fig. 2 is a simplified or diagrammatic elevational view showing the structure without the coils on the various poles of the field-frame.

Essentially, our invention consists of means for providing two cooperating pairs of two alternating-current field-fluxes, which we can distinguish by calling one of the fluxes 4a and the other on. Two loops are also provided, which are mechanically fastened together and mounted for movement. The loops and fields are provided so that one of the loops, which may be designated A, is traversed by the first flux, which may be designated .pm, in one of the pairs of cooperating fluxes,

while the coil-sides 3 and l of said loop A lie in airgaps i and 6, which are traversed by a second flux or that pair, said second flux of the loop-A pair being designated rims. The other loop B is inversely related to the other pair of fluxes, which are designated on; and one, respectively. The loop B is traversed by the second flux one, and its coil-sides I3 and I4 lie in airgaps l5 and I6 which are traversed by the first flux m of the second pair of fluxes.

As shown in the drawing, the fluxes are carried by a stack of magnetizable punchings 20, which constitute a field-magnet frame, which may be described as having a central magnetizable disk 2|, and a peripheral yoke-member 22, with various radial magnetic legs 3|, 32, 33, 34, 35, and 3' joining the two. On the two sides of the radial leg 32, the yoke 22 is provided with inwardly projecting pole-pieces 45 and 46, defining the airgaps 5 and 6 which are between the ends of these pole-pieces and the central disk 2|. On the two sides of the radial leg 35 are two other pole-pieces and 56, which extend inwardly from the outer yoke 22, to provide the airgaps l5 and II.

The radial leg 32 is excited by a coil 6|, which produces the flux 4m, the return-path for said flux being through the two radial legs 3! and 33, as indicated in Fig. 1. The pole-pieces 45 and 46 are excited with serially connected coils 62 and 63 which produce, respectively, north and south poles (at any instant), traversed by the flux 4m. These fluxes cooperate with the loop A, as shown and described.

On the loop-B side of the apparatus, the radial leg 35 is excited by a coil 64 so as to be traversed by the fluxosn, the return-paths for which are through the radial legs 34 and 33, as shown. The two pole-pieces 55 and 56 are excited by coils 65 and 86, so as to provide, at any instant, alternately north and south poles traversed by the flux 4am.

The various coils are excited, in either series or parallel circuit-relation, as may be desired, to provide the required exciting-currents. In the particular form illustrated, the coils 64, 62, and 63 ale-source, so that are excited from a suitable alternatingcurrent source: marked E, which may be a voltthey are all traversed by an exciting-current ml. The other three coils, I, II, and II, are shown as being connected together in series, in another circuit which isenergized from a second alternating-current source, marked I, which may be a current-source, which supplies the exciting-current n! to the said coils.

The two loops A and B are mechanically connected together, as by cross-pieces II and 12, which may be insulating, if desired, the central portions of the cross-pieces being carried by vertically extending pivots l3 and 14, respectively. A contact-arm II is also provided, for cooperating with contact-points ll of any suitable relay-circuit which is to be controlled by our relay.

The operation may be derived as follows.

The instantaneous values of the two relay ex citing-currents nut and 111 may be written v21: sin wt and V2nf sin (wt-), where O is the angle bywhichIlagsE, andEandIarethermsInaB- nitudes of E and I.

The fluxes it and 4s lag behind their respective inducing-currents by a certain angle a, but by reason of the symmetry of the construction, that angle is the same for both of these fluxes.

The fluxes e and a lag behind their respective inducing-currents by a diilerent angle b, but by reason of the symmetry of the construction, that angle also is the same for both of these fluxes. V

The loop-currents Ia and In lag behind their respective inducing-fluxes o and o by a certain angle c, which, because the loops are identical, is the same for both loops.

The current Ia, flowing in the loop-sides I and l, react with the flux o in the airgaps I and I. to produce a torque Ta in a clockwise direction, which we may call negative.

The current In, flowing in the loop-sides l8 and l4, react with the flux a in the airgapa I5 and It, to produce a torque T1; in a counterclockwise direction, which we may call positive.

Each of the instantaneous torques is and in is the product of the instantaneous value of its loopcurrent, times the instantaneous value of its airgap flux, so that the total instantaneous torque is It will be noted that the double-frequency terms, involving the cosine of 2101. minus a certain angle, cancel each other, being exactly equal and opposite.

The total torque Tn--Ta is therefore a steady torque, without any pulsations; regardless of the angle 0 between the alternating-current quantities whose relative directions are being responded to. v The total torque is It is to be noted that 0, in a general sense, is simply the angle between the two relay-currents ml! and 1:1, or the time-phase angle between the two relay-fluxes o and a It need not be the loop-systems for circulating currents,

line-power-iactor angle, which we may designate 0i. but it may be any angle such as 0:013). 80, also the two relay-fluxes a and a or their exciting-currents M and mlt', need not be derived from a line-current and a line-voltage, respectively, but they may be any two single-phase quantities, of the same frequen whose phasa or directions are to be compared, in will have a zero respo se phase-angle between the two quantities.

While we have illustrated our invention in but a single form of embodiment, we thus believe tint the principles of the applications of physical laws are quite generic, and we desire that our appended claims shall be given the broadest interpretation consistent with their nguage.

We claim as our invention:

-1. A substantially non-vibrating single-phase torque-producing electro-responsive device comprising a relatively stationary flux-producin means for producing a flrst alternating flux or fluxes in response to a first electrical quantity and a second alternating flux or fluxes in mponse to a second electrical quantity, said flux-producing means comprising magnetic circuits for said fluxes, at least some of said magnetic circuits having an airgap or airgaps; and a relatively movable member comprising means, in said airgap or airgaps, for providing first and second closed paths for circulating currents, a flrst circulatingcurrent path being so disposed that it is interlinked by a first flux while its circulating current flows in an airgap or airgaps of a second flux, and a second circulating-current path being so disposed that it is interlinked by a second flux while its circulating current flows in an airgap or airgaps of a flrst flux.

2. A substantially non-vibrating single-phase torque-producing electro-responsive device com prising a relatively stationary flux-produchrg means for producing a first alternating flux or fluxes in response to a first electrical quantity and a second alternating flux or fluxes in response to a second electrical quantity, said flux-producing means comprising magnetic circuits for said fluxes, at least some of said magnetic circuits having an airgap or airgaps; and a relatively movable member comprising means, in said airgap or airgaps, for providing first and second a first loopsystem being so disposed that it is interlinked by a flrst flux while its circulating current flows in an airgap or airgaps of a second flux, and a second loop-system being so disposed that it is interlinked by a second flux while its circulating current flows in an airgap or airgaps of a first flux.

3. A substantially non-vibrating single-phase torque-producing electro-responsive device comprising a relatively stationary flux-plodudng means for producing a first alternating flux or fluxes in response to a first electrical quantity and a second alternating flux or fluxes in respons to a second electrical quantity, said flux-producing means comprising a first magnetic circuit and a fourth magnetic circuit both traversed by substantially said flrst flux, and a secon magnetic circuit and a third magnetic circuit both traversed by substantially said second flux, at least said second and fourth magnetic circuits each having an airgap or airgaps; and a relatively movable member comprising means, in said airgap or airgaps, for providing flrst and second closed paths for circulating currents, a first circulating-current path being so disposed that it is interlinked by the flux oi the first magnetic circuit while its circulating current flows in an airgap or airgaps of the second magnetic circuit, and a second circulating-current path being sodisposedthatitisinterlinkedbythefiuxof the third magnetic circuit while its circulating current flows in an airgap or airgaps of the fourth magnetic circuit.

4. A substantially non-vibrating single-phase torque-producing electro-mponsive device comprising a relatively stationary flux-producing means for producing a first alternating fiux or fiuxesinresponsetoafirstelectricalquantity andasecond alternatingfiuxorfiuxesinrespouse to a second electrical quantity, said fluxproducing means comprising a first magnetic circuit and a fourth magnetic circuit both traversed by substantially said first fiux, and a second magnetic circuit and a third magnetic circuit both traversed by substantially said second flux, the second and fourth magnetic circuits each having two airgaps therein; and a relatively movable member comprising means, in said airgap or airgaps, for providing first and second loop-systems for circulating currents, the first loopsystem being so disposed that it is interlinked by the first magnetic circuit and so that portions of said first loop-system lie in the air-gaps of the second magnetic circuit, and the second loopy beingsodisposedthatitisinterlinkedhythethird magnetic circuit and so that portions of said second loop-system lie in the airgaps of the fourth magnetic circuit.

5. A substantially non-vibrating single-phase torque-producing electroqesponsive device comprising a relatively stationary flux-producing means for producing a first alternating flux and aimirthalternatingfluxinrc p toafirst electrical quantity and a second alternating flux andathirdalternatingfluxinresponsetoasccond electrical quantity. said flux-producingmeans comprising magnetic circuits for said fluxes, the magnetic circuits for at least the second and fourth fluxes each having an airgap or airgfl-lfi; and a relatively movable member comprising means, in said airgap or airgaps, for providing first and second closed paths for circulating currents, a first circulating-current path being so disposed that it is interlinked by the magnetic circuit for the first flux while its circiflatin current flows in an che p or ai B -P of the magit is interlinked by the magnetic circuit for the third flux while its circulatin current flows in an airgap or air-gaps or the magnetic circuit for the fourth flux.

6. A substantially non-vibrating single-phase torque-producing electro-responsive device comprising a relatively stationary flux-producing means for producing a first alternating flux and afourthalternatingfluxinresponsctoafirst electrical quantity and a second alternating flux andathirdalternatingfluxinrsponsetoasecond electrical quantity. said flux-producing means comprising ma netic circuits for said fluxes, the magnetic circuits for at least the second and fourth fiuxes each having an air ap or airgaps; and a relatively movable member comprising means, in said airgap or air-g ps, for providing first and second loop-systems for circulating currents, a first loopstem being o disposed that it is interlinked by the magnetic circuit for the first fiux while its circulating current flows in an second fiux. and a second loop-system being so disposed that it is interlinked by the magnetic circuit for the third flux while its circulating current fiows in an airgap or airgaps of the magnetic circuit for the fourth flux.

I. A substantially non-vibratin single-phase torque-producing electro-responsive device comprising a relatively stationary flux-producing means for producing a first alternating flux and a fourth alternating flux in response'to a first electrical quantity and a second alternating fiux and a third alternating flux in response to a second elecllical quantity, said flux-produci means comprising magnetic circuits for said fluxes, the magnetic circuits for the second and fourth fluxes each having two airgaps therein; and a relatively movable member comprising means, in saidp or airgaps, for providing first and second loop-systems for circulatin currents, the first loop-system being so disposed that it is interlinked by the magnetic circuit for the first flux and so that portions of said first loopsystem lie in the airgaps of the magnetic circuit for the second flux, and the second loop-system being so disposed that it is interlinked by the magnetic circuit for the third flux and so that portions of said second loop-system lie in the airgaps of the magnetic circuit for the fourth flux.

8. The invention as defined in claim 5, characterized by the product of the first and second fluxes being at all times substantially identical, in magnitude, with the product of the third and fourth fluxes, and the phase-angle between the first and second fluxes being at all times substantially the same as the phase-angle between the third and fourth fiuxes.

9. The invention as defined in claim 6, characteriaed by the product of the first and second fluxes being at an times substantially identical, in magnitude, with the product of the third and fourth fluxes, and the phase-angle between the first and second fluxes heir: at all times substantially the same as the phase-angle between the third and fourth fluxes.

10. The invention as defined in claim 7, characterized by the product of the first and second fluxes being at all times substantially identical, in magnitude, with the product of the third and fourth fluxes, and the phase-angle between the first and second fluxes being at all times substantially the same as the phase-angle between the third and fourth fluxes.

11. A substantially non-vibrating single-phase torque-producing electro-responsive device comprising contro1circuit means for supplying two out of phase single phase exciting currents, torque-producing means comprising two opposing torque-producing elements each producing a torque responsive to the product of a torque-producing alternating current times a torque-producing alternating fiux times a predetermined fimction of the phase-angle between them, means for producing the torque-producing current of the first element and the torque-producing flux of the second element in response to the first exciting-current, with a predetermined phase-angle relationship other than 90 between current and flux in response to said first exciting-current, and means for producing the torque-producing current of the second element and the torqueproducing flux of the first element in response to the second exciting-current, with said predetermined phase-angle relationship between current and flux in response to said second excitingairgap or airgaps or the magnetic circuit for the 75 current.

determined function of the sum 0! s constsnt angle other than 90 and the phase-mile between Illd exciting-currents, and in such manner that the other or said elements is responsive to the product of said exciting-currents times said wede function or the diiierence between said constant uncle and said phase-angle.

SHIRLEY L. GOLDBBOROUGH.

MEHRING.

13. A lubstsntisily non-vibrating single-phase torque-producing electro-resnonsive device comwining control-circuit means for supplying two out of nhsse single phase exciting currents, torque-producing means comprising two opposing wsttmetricsiiy responsive elements. and means tor said two wuttmetricaily responsive elements from said two exciting-currents in such mar that one of said elements is responsive to the product 01' said exciting-currents times a pre- 10 ARTHUR. C. 

